Measuring and indicating system



Sept. 4, 1956 A. H. DlcKlNsoN ErAL 2,761,966

MEASURING AND INDICATING SYSTEM Original Filed-May 26, 1951 4Sheets-Sheet l BY Z l ATTORNEY 4 Sheets-Sheet 2 Sept. 4, 1956 A HDICKINSON ETAL MEASURING AND INDICATING SYSTEM Original Filed May 26,1951 l I I I I I I I I I I I I I I I I I l: II II 'l 'l I: I i! i: li i:|I I Il I Il :I |l |I :z )l Il I: ,l II Il Il II Il 'x E: II l| lI II :I

INVENTORS ARTHUR H. DICKINSON ROBERT OPAULSEN BY ATTORNEY A. H.DlcKlNsoN ET A1. 2,761,966

MEASURING AND INDICATING SYSTEM Sept. 4, 1956 4 Sheets-Sheet 3 OriginalFiled May 26, 1951 N ON E mm@ @E 0% N mmp .m EHC O v l l I I I l l l l lI I l l l l I l I l l I I l l I I l l l l l l I l l l l l I l l l l I ll l I I l l I I l l I I I l I I I I I l l I l l I l IIJ NRT n A l. HE m@mm Y B am. 1 2N M mw mm1 KQ. www W NN N @NN mm o wm. v2 NNN N N .am

Sept. 4, 1956 A. H. DlcKlNsoN ErAL 2,761,966

MEASURING AND INDICATING SYSTEM Original Filed May 26, 1951 4Shees-Sheet 4 ARTHUR H.D\oK\NsoN ROBERT QPAULSEN BY Z ATTORNEY UnitedStates Patent ce annatel iltartenteol Sept. 4, 1956 MEASURING ANDINDICATING SYSTEM Arthur H. Dickinson, Greenwich, Conn., and Robert C.Paulsen, West Caldwell, N. J., assiguors to International BusinessMachines Corporation, New York, N. Y., a corporation of New YorkOriginal application May 26, 1951, Serial No. 228,432, now Patent No.2,717,994, dated September 13, 1955. Divided and this applicationFebruary 7, 1952, Serial No.270,414

Claims. (Cl. Z50-27) This application is a division of applicationSerial No. 228,432, tiled May 26, 1951, now Patent 2,717,994 issuedSeptember 13, 1955, which invention relates to measuring and indicatingsystems, and more particularly to improved means for measuring andindicating or manifesting the value of a variable quantity such as anelectrical potential or a physical displacement.

A principal object of the present invention is to provide digitalmanifestation of a variable quantity with a high degree of linearity,sensitivity, accuracy and reproducibility.

Another object of the present invention is the provision of digitalmanifestation of a variable quantity without appreciably loading thesource of the quantity.

A further object of the present invention is to provide a plurality ofsuccessive digital manifestations of a variable quantity automatically.

Still another object of the present invention is to provide a digitalmanifestation which is equal to the actual value of a variable quantity.

An additional object of the present invention is the provision of adigital manifestation which is proportional to the actual value of avariable quantity.

In accordance with the present invention, there is provided a variablequantity measuring and manifesting device which comprises thecombination of a plurality of structural elements. These elementsinclude a source of oscillations, and a register responsive to theseoscillations. Gating means are interposed between the source ofoscillations and the register, and these gating means are adapted tocontrol the flow of oscillations therebetween. Translating means areprovided which are adapted for developing a potential proportional tothe setting of the register. Means are provided for comparing thispotential with the variable quantity to be measured, and for actuatingthe gating means when the potential is proportional to the variablequantity. Means are also provided for manifesting or indicating thesetting of the register.

1n accordance with an important feature of the present invention, themeans responsive to the comparing means for actuating the gating meansare also adapted for causing a delayed resetting of the register to apredetermined value when the changing potential is proportional to thevariable quantity, and the means for manifesting the setting of theregister are arranged to operate between the actuation of the gatingmeans and the delayed resetting of the register to the above-mentionedpredeter mined value. In accordance with this feature of the presentinvention, a plurality of successive digital manifestations of avariable quantity may be automatically secured.

Other objects and features of the present invention will be pointed outin the following description and claims and illustrated in theaccompanying drawings, which disclose, by way of example, the principleof the invention and the best mode, which has been contemplated, ofapplying that principle.

ln the drawings, in which like reference numerals designate likecomponents:

Fig. l is a block diagram of a measuring and indicating device inaccordance with the present invention;

Fig. 2 is a schematic circuit diagram of the oscillator, gate, andcontroller and resetter units of Fig. 1;

Fig. 3 is a schematic circuit diagram of the register or counter andburmrer unit of Fig. 1, certain of the duplicate elements having beenillustrated in block form.

Fig. 4 is a schematic circuit diagram of the translator unit of Fig. l,blocks being used to represent certain of the duplicate elements toavoid unnecessary complexity; and

Fig. 5 is a schematic circuit diagram of the comparer unit and thesource of Variable quantity unit of Fig. l.

The .system as a whole Referring to Fig. 1, there is shown a variablequantity measuring and manifesting device in accordance with tirepresent invention which comprises an oscillator unit 10, a gate unit 11,a controller and resetter unit A12, a register or counter and bufferunit 13, a translator unit 14, a comparer unit 15, and a source ofvariable quantity unit 16. When the system is in operation, oscillatoriti produces a steady train of pulses which are supplied to gate unit11. Gate unit 11 is under control or" unit l2. Each complete cycle ofoperation of the system comprises two portions, the iirst of which isutilized for determining the digital value of the unknown variablequantity, and the second of which is utilized for manitesting orindicating this value. Let it 'oe assumed that a cycle has been manuallyinitiated, so that controller unit 12 causes gate unit 11 to open. Underthis condition, the pulses from oscillator unit 10 pass through gateunit 11 into counter and buffer unit 13, in which they are counted.

The digital value developed in counter and buffer unit 13 is nowconverted, by means of translator unit 14, into an electrical potentialwhich is a direct function of the setting of counter unit 13. Thispotential is compared, in comparer unit 15, with the unknown variablequantity provided by unit 16. When the potential from unit 14 isproportional to or equal to the variable quantity from unit 16, comparerunit 15 causes controller and resetter unit 12 to close gate 11. Thiscorresponds with the end of the iirst portion of the operating cycle.After a short delay corresponding with the second portion of theoperating cycle and during which the counter setting may be read orotherwise utilized, controller and resetter unit 12 causes counter andbuffer unit 13 to be reset to its initial value, thus preparing thisunit for the next successive operating cycle. This initial value may be0000 or any other desired setting.

The oscillator, gate and controller units Referring to Fig. 2 of thedrawings, oscillator 16 comprises an electron discharge device 20,preferably of the double tridoe type, arranged to operate as aconventional multivibrator to provide a continuous train of outputpulses. These pulses are supplied, by means of a coupling capacitor 21,to the suppressor electrode 22 of an electron discharge device 23,preferably of the pentode type with its cathode 24 grounded as shown.Suitable directcurrent bias is applied to suppressor electrode 22through a resistor 25 the lower end of which is connected to the movablearm 26 of a potentiometer 27, which in turn is shunted between groundand a suitable source of negative potential 23. Arm 26 is bypassed tosource 2Sk by a capacitor 29.

Electron discharge device 23 comprises the gate. Control electrode 35 isconnected to junction 31 in a potential divider comprising resistors 32,33 and 34 in series between positive potential source 35 and negativepotential source 28. The potential of junction 31 is normally such that`discharge device 23 is substantially nonconductive. Screen electrode 36of discharge device 23 is connected by a resistor 37 to positivepotential source 35, and is bypassed to ground by a capacitor 38. Aresistor 39 is connected between positive potential Asource 35 and anode40 of ldischarge device 23, and a lead 41 is connected to anode 40 forthe purpose of supplying output pulses Yfrom the gate to counter andbutter unit 13 (Fig. .3).

For Ythe purpose of manually causing the gate to open, there is provideda capacitor 42 lconnected between negative potential source 23 and themovable arm 43 of a SPDT switch 44, the left-hand terminal 45 of whichconnects to junction 31 and the right-hand terminal 46 connects to thejunction of resistors 47 and 48 in series bctween positive `potentialsource 35 and ground. When switch arm 43 is thrown to the right,capacitor 42 'becomes charged to a` potential, corresponding to thepotential diierence between switch terminal 46 and source 28. Throwingswitch arm 43 to the left causes capacitor 42 to discharge, raising thepotential of junction 31 to somewhat above ground potential, so thatgate discharge device 23 may conduct whenever a positive-going pulse isapplied to its suppressor electrode 22 by oscillator 10 throughcapacitor 21. This in turn causes a negativegoing pulse to be developedin output lead 41 for application to counter unit -13 (Fig. 3). A gatetrigger circuit 49 is provided, comprising an electron discharge device50 preferably of the type having a'pair'of triode portions. This deviceoperates as a conventional bi-stable multivibrator. Cathodes 51 and 52are grounded. Right-hand control electrode 53 is connected to junction31. Left-hand anode 54 is connected to the junction of resistors 32 and33, and a. capacitor 55 is shunted across resistor 33. A series networkcomprising resistors 56, 57 and 53 is connected between positivepotential source 35 and negative potential source 28. Right-hand anode59 of discharge device 50 is connected to junction 60 of resistors 56and 57, and left-hand control electrode 61 is connected to junction 62of resistors 57 and 58. A capacitor 63 is shunted across resistor 57.The potentials of junctions 31 and 62 are normally such that theleft-hand portion of discharge device 50is conductive and its right-handportion non-conductive. This condition may be designated the oftcondition of the gate trigger circuit, the opposite condition'beingdesignated the on condition. The latter condition results, for example,when switch arrn 43 is thrown to the left.

For the purpose of turning gate trigger circuit 49 oi automatically,and'hence causing gate 11 to be closed at a desired time, positivepulses are developed in comparer unit 15 (Fig. 5) and supplied bymeanso'f lead 65 VtoY left-hand control electrode 66 of dual electrondischarge device 67, cathodes 68 and 68a of which are grounded.Resistors 69 and 70 are connected in series between lefthand anode 71'of discharge device 67 and positive potential source 35, and theirjunction 72 is coupled by means of a capacitor 73 to junction 31. Theleft-hand portion of 'discharge device 67 is maintained normallynon-conductive by the application, through a resistor 74, of a suitablenegative potential to control electrode 66,. this potential beingderived from a potentiometer 75 shunted between groundV and negativepotential source 28, the movable arm being bypassed to ground by acapacitor 76. A positivepulse applied to control electrode 66 by lead 65causes the left-hand portion of discharge device 67 to becomemomentarily conductive, the resultant negative-going pulse at junction72 turning gate trigger circuit 49 on? and causing gate 11 to be closed.

To provide automatic resetting of the system after a predetermined timeinterval, -lead 65 is also connected to control electrode 77 of anelectron discharge device 7.8',

preferably of the triode type with its cathode 79 grounded. Resistors 80and 81 are connected in series between anode 82 of discharge device 78and positive potential source 35. Junction 83 of resistors 80 and 81 iscoupled by a capacitor 84 to left-hand control electrode 85 of a dualelectron discharge device 86 having its cathodes S7 and 88 grounded andYbeing arranged, with the associated'components, to loperate as aconventional self-restoring ,trigger circuit 89 in which the left-handportion is normally conductive, this condition being :designated theV ocondition of the circuit. A series network comprising resistors 90, 91and 92 is connected between positive potential source 35 and negativepotential source 2 8. 'The junction v9 3 of resistors 90 and 91 isconnected to righthand anode 94 of discharge device 86. A capacitor95 isshunted across resistor 91. Resistors 96 and 97 are connected betweenleft-handl anode 98 of discharge device 86 and positive potential source35. A neon indicator tube 99 is connected between left-hand anode 98 andground. Right-hand control electrode'liit)V vof dischargeV device 86 isconnected through a resistor 101 to the movable armof a potentiometer102 shunted between ground andk negative potential source 28, themovable being bypassed to source 28 by a capacitor 103. A capacitor 104is connected between vright-hand control electrode and left-hand anodeV98.

The junction 105 of resistors 96 and 97 is coupled by a capacitor 106 toleft-hand control electrodeV of afdual electron discharge device 108having its cathodes 109: and 110 grounded and being arranged, with theassociated components, to operate as a conventional selfrestoringtrigger circuitY 111. A series network comprising resistors 112, 113.and114 is connected betweenposi-Z tive potential source 35 and negativepotential source 28, the junction 115 between resistors 112 and 113being connected to right-hand anode 116 of discharge device 108,`and thejunction 117 of resistors 113 and 114 being connected to left-handcontrol electrode 107. A capacitorLV 118 is shunted across resistor 113.Resistors 119 and 120 in series are connected between the left-handanode 121 of discharge device 108 and positive potential source 35. Aneon indicator tube 122 is connected between lefthand anode 121andrground. Right-hand control electrode v123 of discharge device 108 isconnected through a resistor' 124 to the movable armof a potentiometer1251shunted between ground and negativepotential source.

28, the movable arm of the potentiometer being bypassed to source 28 bya capacitor 126. A capacitor l127 is connected 'between left-hand anode121` and right-hand Junction 115 is coupled by'aA control electrode 123.capacitor'lZS to `right-hand control electrode 129 of discharge device67. A potential suitablefor maintaining the right-'hand portion ofdischarge device 67 normally" non-conductiveY is applied to right-handcontrol electrode 129thro1igh a resistr 13@ from a voltage dividercomprising resistors 131 and 132 connected in series between ground andnegative potential source'ZSQ VResistorsy 133 and 1347 are connectedbetween right-hand anode 135 I of discharge device 67 'and positivepotential source 3 5,

their junctionbeing coupled by a capacitor 136 toV lefthand controlelectrode 61 of discharge device 50.

1n operation, automatic `resetting of the system after',k

a predetermined time interval 'is achieved in the following manner. Apositive pulse Von lead 6,5 renders discharge device 78 conductive,producing a negative-goingl pulse at junction S3. This in turn turnsself-restoringffrigger' circuitV 89 on, inwhich condition it remains fora period of time determined bythe values of capacitor.

104 and resistors97, 96 and 101, and by the bias rpotential due to thesetting of potentiometer 102. When trigger..cir'cuit.89.switches off,the negative-going pulse at junction 105. causes self-restoring triggercircuit 111.to be .switched on, a condition which .is maintained for anvintervalof time .dependent upon the valuesof thecomponents comprisingthis circuit. When trigger circulrt e at junction 62. This pulse causesgate trigger circuit 49v to switch on, which in turnl causes gate 11 toopen, thus initiating a new complete cycle.

For the purpose of actuating the resetting diodes in counter and butterunit 13 (Fig. 3), there is provided an electron discharge device 137(Fig. 2), preferably of the triode type and having a cathode 13Sconnected by means of a resistor 139 to negative potential source 28.Cathode 138 isalso connected to an output terminal 140. Junction 93 iscoupled by means of a capacitor 141 to control electrode 142 of device137. To maintain the desired normal degree of conductivity of dischargedevice 137,` a network comprising resistors 143 and 144 is connectedbetween ground and negative pothrough capacitor 141 to control`electrode 142 of dis-` charge device 137, thus rendering this dischargedevice susbtantially more conductive and producing an appreciablygreater potential drop across resistor 139. This potential drop isutilized, through output terminal 140, in a manner to be described inconnection with Fig. 3.

For .theV pumose of maintaining extinguished the in-V dicators forming apart of counter and buier unit 13 (Fig. 3) during a desired portion ofeach complete cycle of operation, there is provided an electrondischarge device 146, preferably of the pentode type and having itscathode 147 and its suppressor electrode 148 grounded. Control electrode149 of discharge device 146 isvconnected to junction 62 of gate triggercircuit 49. Screen electrode 150 and anode 151 of discharge device`146are connected together and to an output terminal 152. In operation,discharge device 146 is normally non-conductive, thus interrupting thereturn path for .the indicatorsv of counter and buffer unit 13 (Fig.3)'. At the beginning of a cycle, the negative-going pulse which isdeveloped at junction 62 switches'trigger circuit49 on, as explainedabove, and theresultant negative potential is applied to controlelectrode 149 of discharge device 146, thus rendering this dischargedevice substantially non-conductive, thereby extinguishing theindicators of the counter unit. These are maintained in this conditionfor a desired portion of the complete operating cycle.

The counter and buer unit Referring to Fig. 3 of thedrawings, theregister or counter comprises four denominational orders, respectivelydesignated as the units order 155, the tens order 156, the hundredsorder 157, and the thousands order 158. Associated with the counters arecorresponding buiers 159, 160, 161 and 162. To avoid unnecessarycomplication, only units order 155 of the counter and associated buier159 are shown in detail, the remaining orders of the counter and theother buiers being iden,- tical in internal arrangement.

Each order of the counter is constructed and operates as disclosed andclaimed in copending application Serial No. 654,175 of Byron E. Phelps,led March 13, 1946, now Patent No. 2,584,811, granted February 5, 1952,and assigned to the same assignee as the present application. Unitsorder 155 comprises four bi-stable trigger circuits 163, 164, 165 and166, each including an electron discharge device of the dual type asshown, and a delayed action blocking tube 167. Associated with theleft-hand portion of each discharge'device of circuits 163-166 is a'neonindicator or'glow tube, these tubes being designated respectively 168,169, and 171. As input pulses are applied by means of lead 41, unitsorder 155 manifests or counts on a tens notational basis and, uponpassage from 9 to 0, a carry is passed from units order 155 to tensorder 156.

Assuming for the moment lthat units order 155 is in its initialcondition, i. e., set for areading of 00,00, the left-hand portion ofeach of the discharge devices of trigger circuits 163-166 is conductiveand the righthand portions of these devices are non-conductive. This maybe designated the oi condition of each trigger circuit. A negative-goinginput pulse on lead 41 will have no effect upon the right-hand portionof the discharge device of trigger Vcircuit 163, since the controlelectrode of this portion is already su'iciently negative torender thisportion non-conductive, but the negative-going input pulse will causethe left-hand portion of the discharge device of trigger circuit 163 toshift from its conductive to its non-conductive condition, since thepotential of the control electrode of this portion is drivensubstantially negative from its original value. This condition may bedesignated the on condition of each trigger circuit. This in turn causesthe left-hand anode to rise in potential, so that indicator tube 168breaks down and produces a visible glow.

The trigger circuits comprising each order are connected in tandem, theimpulses to be counted being introduced at one point only. Accordingly,the trigger circuits in each order of the counter eect the followingpattern for each ten pulses applied to the input, units order 155 beingused as an illustration:

Trigger Circuit Input Pulse 011,-- Off.V onon. oir..- on. off.. on. onon. 011--.- on. 0n on. On OE. 0o.--- on. Ot, On. on off.

For the purpose of restoring trigger circuits 163-166 to their oficondition upon the completion of each coun-t, there are provided diodes172, 173, 174 and 1715, having their cathodes connected respectively tothe left-hand control electrodes of the discharge devices of triggercircuits 163-166, and having their anodes each connected to terminal 140(Fig. 2). 1t will be recalled that this terminal is renderedsubstantially positive nearr the completion of each operating cycle,thereby causing iodes 172-175 to become conductive, which in turnswitches o any of trigger circuits 163-166 which are on. Thus thecounter is automatically reset to 0000 in preparation for lthe nextcounting cycle.

Associated with trigger circuits 163-166 are butler elements comprisingrespectively dual electron discharge devices 176, 177, 173 and`179 whichtogether comprise units order bu'er 159. It will be understood, ofcourse, that each dual discharge device may be replaced by two separatedischarge devices if desired, or by one discharge device and a rectifierhaving a relatively high ratiov between its forward and backwardresistances. When trigger circuit 163 is on, the right-hand controlelectrode of its dual electron discharge device is at substantiallyground potential. As shown, this electrode is connected to the left-handcontrol electrode of discharge device 176, so that this portion of thisdevice is highly conductive and there is a substantial potential dropacross associated load impedance element or resistor connected betweenthe left-hand anode of device 176 and a sourcev 181 of high positivepotential; A second impedance eleazen-aes ment `vor a resistor `1,82 isconnected between the left and right-hand anodes .of xdischarge .device176, the righth;,. d. anode being .connectedto the right-hand. controlelr t1-ode to forni a diode :and being .connected through a thirdimpedance element or resistor 183 to 'a source 1 84 of high negativepotential. Resistors 182 and 183 are so proportioned `that when theleft-hand portion of discharge device 176 is highly conductive theright-hand anode of this `discharge device is substantially negativewith `respect to ground. Under this conditiomthe righthand portion ofdischarge device 176 is'non-conductive and has no eiect upon theoperation of the buffer. On the other hand, when trigger circuit 16,3 isoff, the lefthand portion of discharge device 176 is non-conductive, s othat the potential of the righthandanode of discharge device 17.61 .tmdsto rise above ground potential. The right-hand portion of this dischargedevice comprises a clamping means which provides a clamping action,however, with `,the result that the right-hand anode of this device1under this condition is maintained at a potential very close to groundpotential. By means of a lead 1385, the potential of this anode isapplied to units order 19.0 of translator unit 14 (Fig. 4). Similaroutput potenllS are developed b-y discharge devices 177, 17S and 179,and passed on to the units order of translator unit 14 respectively byleads 18,6, 187 and 188. IIn the manner just described, therefore, va.plurality of output voltages are provided, each of which is eithersubstantially negative with respect to ground or `maintained veryclosely at ground potential, depending upon whether or not thecorresponding trigger .circuit of units order 155 of the counter is onor off; It will be understood that similar output potentials aredeveloped in buffers 160, 161 and 1'62, and passed on to thecorresponding orders 191, 192 and193 of translator unit 14K-Fig. 4).

The translator unil.

Referring to Fig. 4 of `the drawings, the translator unit comprises theorder translator`190, thetfefns order translator 19,1, hundreds .ordertranslator 192, and the thousands order ltranslator 19.3, associatedrespectively with buers v159, 160, 161 and 162 (Fig. 3). Only unitstranslator 190 is shown and described indetail, since translators '191,192 and 193 are constructed and operate in au identical manner. A Y Y Yv 'Y The translator comprises impedance elements or resistors 194-209connected `between high positive potential source 181 and translatoroutput terminal 210. Units order translator 190 comprises electrondischarge devices 211, 212, 213 and v214, preferably of the pentodetype, respectively having cathodes 215, 216, 217 and 218, controlelectrodes 219, 22.0, 221 and 222, and anodes 223, 224, 225 and 226. Thesuppressor electrodes of these discharge'devices are connectedrespectively to their cathodes, and the screen electrodes are connectedto positive potential source 35.

Cathode 215 of discharge device 211 is connected to y ground through anadjustable resistor 227 Control electrode 219 is connected by means of aresistor 228 to lead 185 kfrom buffer 159 (Fig. 3). Anode 223 isconnected to the junction of resistors 194 and 195. Discharge devicesv212, 213 and 214 have their cathodes 216-218 connected to groundrespectively through adjustable resistors 229, 230 and 231. Theircontrol electrodes 221)- 222 are connected by resistors 232, 233 and 234respectively to leads 186, 187 and 188 from buffer 159 (Fig. 3). Anode224 of discharge device 212 is connected to the junction of resistorsv19.5 and 196, anode 225 of discharge device 213 to the junction ofresistors 196 and 197, and anode 226 of discharge device 214 to thejunction of resistors 197 and 198. Although not shown in detail in Fig.4, it will be understood thatsimilar connections from the terminals ofresistors 19E-209 are made to the anodes of the tour electron dischargedevices disposed in each of translators 191, 192 and 193.

lf will be .recalled .ffamthe dammi@ 0f Fis- .34h41 leads .18S-188 lare.either .substantially negative with respeer to'ground or .aremaintained very1 closely at potential; .depending upon whether or .notcorrespond.-

ing trigger 'circuit of lunits .order 15.5 lof the 'counter'is onV orort. Assume f orfthe moment trigger circuit .163 :of counterv ..155 ,isoth Under this condition, lead 185 is very closely at ground'potential,so .that electron discharge' device 211 is conductive, the degree ofconductivity. being readily Afa'cljulst ed by means of adjustableresistor 227. Because .of the inherent characteristic of a pentode,resultant current oiv -nertiaitis .substantially uniform in spite.fofvariationsi-n the potential drop across the dis-1V charge device.VThis conductivity of .discharge V`device, .2 11 prcdllcss .apredetermined potential ldren across. resister 194. Now let itheassugned that trigger circuit 16,3 :of counter 155 (Fig. 3) is on,:sothat leadlSS 4is Amaintained at a vsubstantiallynegative potentialwith @Speer toground. This renders discharge device 2,11 non-conductive`with, theresult that `thererisr no potential drop across resistor.

19.4y due to Yanode current vlowing in discharge device 211. Asimilar-:operation occurs in each Of the remaining.:dis-` charge devicescomprising. the translator unit, so that the tot-al potential .'dlpacross resistors v19A-2.09 .due .to -the anode-currents of thesedischarge devices is a direct func# tion :of the .on and oli patternestablished` :in counters .155, 1561,v 157 and .158. By proper choice ofthe values of resistors 319.4409, it' :is possible to secure a. desiredpotential .ditference between :positive potential source 181correspondingwith the count momentarily present inv they counternnits.of Fig. 3.

By way of specific example,y let it be assumed that following resistancevalues,

resistors 194-209have fthe expressed inohms:

is adjusted to have an anode .current .of 1.-0 milliampere when it isconductive. Under these conditions, if all 16 electron discharge devicesare conductive Ythe total potential drop between positive potentialsource 181 and output terminal 210 due -to their anode currents will be166.65

v volts. This is the condition which corresponds with the (G-setting ofthe counter; Y Assume now that the counter has advanced to 00 01, Vsothat dischargev device 211 is rendered non-,conductive and the currentthrough resistor 194 is 0.001"V ampere less than previously, with theresult that the potentia or output terminal 2 10'rises toward that ofpositive potential source 181 by 0.01 volt. Upon reaching the maximumcount of 9999, output terminal 210 will have risentoward p ositivepotential source 181 by a total of 99.99 volts.

It will be seen'frorn this specic example, therefore, that the values ofresistors 194-209 are such'that, as the counter progresses incrementallyfrom OOOOto 9999, the

Vvoltage diierence between output terminal 210y and positive potentialsourcey 181 decreases. by 0.01 volt for each unit count applied to theinput of the counter. It is this' potential change which kforrnstheoutput oftrahslator 9 V 14 and which is applied to comparer unit 15(Figs. 1 and The comparer unit Referring -to Fig. 5 of the drawings,terminal 210, comprising the output terminal of translator unit 15 (Fig.4), is connected through a DPDT switch 235 to a junction 236. Junction236 is connected through an SPDT switch 237 to anode 238 of an electrondischarge device 239 of the pentode type. When switches 235 and 237 arein the positions shown, the comparer unit is adapted to utilize anunknown variable quantity comprising an electrical potential. The systemwill first be described for operation with this type of unknown inputvariable.

Cathode 240 of discharge device 239 is grounded through a resistor 241.Control electrode 242 is connected by a switch 243 either to inputterminal 244, to which the unknown potential is applied, or to ground.The potential of screen electrode 297 with respect to cathode 240 ismaintained substantially constant by an arrangement which will bedescribed later. Suppressor electrode 245 is connected to cathode 240.

It will be apparent that the potential of junction 236 with respect toground will be dependent upon the potential drop in resistors 194-209(Fig. 4) due both -to the anode currents of the electron dischargedevices of translator unit 14 and to the anode current of electrondischarge device 239, as well as to the potential drop across resistor241 due to the anode current of the latter discharge device. An increasein the anode current of discharge device 239, such as might be caused byapplying an input potential between .terminal 244 and ground, would tendto decrease the potential between junction 236 and ground. A decrease inthe conductivity of one or more of the electron discharge devices oftranslator unit 14 would tend to cause an increase of potential atjunction 236 with respect to ground.

In order to utilize this effect, there is provided a gaseous dischargedevice 246 having a cathode 247, a control electrode 248 and an anode249. Control electrode 24S is connected to junction 236 by a resistor256. A resistor 251 is connected between positive potential source 181and anode 249. For the purpose of maintaining substantially constant theanode-cathode potential of discharge device 246 so that it will re atiiXed controlelectrode potential, there is provided a series networkbetween positive potential source 181 and ground comprising a resistor252 and an electron discharge device 253, preferably of the pentode typeand having a cathode 254 which is grounded through a resistor 255. Aresistor 256 is connected between cathode 247 of discharge device 246and anode 257 of discharge device 253. Control electrode 258 of device253 is grounded. Screen electrode 259 is connected through an adjustableresistor 260 to positive potential source 35, suitable additionalresistors 261 and 262 being provided and arranged as shown. Suppressorelectrode 263 is connected to cathode 254.

In operation, assuming iirst that counter unit 13 (Fig. 3) is set at0000 and that switch 243 is in its right-hand position, resistor 260 isadjusted so that gaseous device 246 is barely extinguished. In otherwords, a small increase in the potential of junction 236 with respect toground would cause discharge device 246 to re, with the result that alarge positive-going pulse is developed -at cathode 247.

Now let it be assumed that switch 243 is in its lefthand position andthat an unknown potential has been applied to input terminal 244. Thiscauses the potential of junction 236 to decrease with respect to ground,so that control electrode 248 of discharge device 246 becomes morenegative with respect to cathode 247. As previously described, however,counter unit 13 has begun counting, so that the potential drop acrossresistors 194-209 (Fig. 4) gradually decreases until the potential ofjunction 236 with respect to ground rises sutiiciently to causedischarge device 246 to tire. The resultant positivegoing pulse atcathode 247 is applied by means of a capacitor 264 to control electrode265 of an electron discharge device 266, operating as a cathode followerand having its cathode 267 coupled by means of a. capacitor 268 to lead65. The resultant positive-going pulse developed across cathode resistor269 causes the closing of gate unit 11, as previously described inconnection with Fig. 2, thus terminating the first portion of a completeoperating cycle.

For the purpose of extinguishing discharge device 246 very shortly afterit iii-es, there is provided an electron discharge device 270 having acathode 271 connected to positive potential source 35. Control electrode272 of device 279 is connected through a resistor 273 and lead 274 tojunction 66 in gate trigger circuit 49 (Fig. 2). Control electrode 272is bypassed to ground by a capacitor 275. Anode 276 of device 27@ isconnected to anode 249 of discharge device 246. When trigger circuit 49is on during the measuring portion of each cycle, the lefthand portionof discharge device 50 (Fig. 2) is nonconductive and the potential ofjunction 60 is such that v control electrode 272 is substantiallynegative with respect to cathode 271 of discharge device 270, so thatthis device is non-conductive. Upon the ring of discharge device 246,trigger circuit 49 is turned off, the left-hand portion of dischargedevice 50 becoming conductive and the potential of junction 60increasing suciently to render discharge device 270 highly conductive.The resultant additional current flow through resistor 251 causes thepotential of anode 249 of discharge device 246 to fall below that ofcathode 247, thereby extinguishing this discharge device. This conditionis maintained until the measuring portion of the succeeding completecycle is initiated.

In order that the anode current of discharge device 239 shall varylinearly with respect to changes in the unknown potential applied toterminal 244 and hence to its control electrode 242, it is necessarythat the potential of screen electrode 297 remain substantially constantwith respect to that of cathode 240 of discharge device 239. For thepurpose of accomplishing this, there is provided a voltage regulatortube 277, preferably of the cold-cathode type, having its `cathode 278connected through an impedance element or resistor 279 to ground, andhaving its anode 280 connected through an impedance element or resistor281 to positive potential source 181. Screen electrode 297 of dischargedevice 239 is connected to anode 280 of regulator tube 277. There isalso provided an electron discharge device 232, preferably of thetetrode type and having its cathode 233 connected to cathode 278 ofregulator tube 277. Control electrode 284 of discharge device 282 isconnected to control electrode 242 of discharge device 239. Screenelectrode 285 and anode 286 of discharge device 282 are connectedtogether and to positive potential source 181. Since discharge device282 operates as a cathode follower, variations in the potential of itscontrol electrode 284 due to changes in the unknown potential applied toinput terminal 244 are reflected linearly in the potential drop existingacross resistor 279 due to the anode current of discharge device 282.Thus the potential of cathode 283 varies directly as does that ofcathode 24d of discharge device 239. Because of the action of voltageregulator tube 277, its anode 280 remains at a substantially constantpotential above that of its cathode 278, with the result that thedierence in potential between screen electrode 297 and cathode 24@ ofdischarge device 239 remains substantially constant, irrespective of themagnitude of the unknown potential applied between input terminal 244and ground. The provision of this arrangement for securing a linearrelationship between the unknown potential applied to terminal 244 and 1l the anode current of discharge device 239 constitutes an importantfeature of the present invention.

As previously described, counter .and buffer unit 13 (Flg. 3) .supplypotentials to the .control electrodes of the electron discharge devicescomprising translator unit 14 (Fig. 4). Since switching of the triggercircuits in the counter unit is accompanied by time delays, it will beapparent that, during the time such switching occurs, the potentialssupplied by translator unit 14 may be lower or higher than the ultimatelevels achieved Vby the counter unit upon the completion of switching.Accordingly, it is desirable to provide means for preventing suchspurious relatively short-period iluctuations of higher potential from.causing premature operation of the comparer unit without, however,appreciably aecting the response of the system due to relativelylong-.period iluctuations. In order to accomplish this, there isprovided an electron discharge device 287, preferably of the tetrodetype and having its cathode 288 connected through an impedance elementor resistor 289 to a suitable source of .positive potential 290.Resistor 289 is shunted by a capacitor 291. Control electrode 292 ofdischarge device 287 is connected through an impedance element orresistor 293 to translator output terminal 210, and an impedance elementor capacitor 294 is connected between this terminal and cathode 288 vofdischarge device 287. The time constant due to resistor 293 and theinput capacitance of discharge device 287 is preferably of the order ofthe period Vof the spurious short-period uctuations at terminal 210 andsmall compared with the period of the long-period fluctuations. Screenelectrode 295 and anode 296 of discharge device 287 are connected`together and to positive potential source 181.

In operation, discharge device 287 operates as a cathode follower, sothat changes in the potential of control electrode 292 causecorresponding changes in the potential drop across resistor 289, thisrelationship being substan# tially linear. `Capacitor 294 isY thereforealways charged to the same value of potential, and it is of sucientcapacitance to'cause bypassing of any spurious pulses which may bedeveloped at terminal 210 when the trigger circuits of counter unit 13are switching. The purpose of capacitor 291 is merely to augment the`stabilizing action of xcapacitor 294 and, although helpful for thispurpose, it is not .an essential component.

Measuring a `physical displacement The system in accordance with lthepresentinvention as thus far described is adapted Vfor measuring andindicating the value of an unknown electrical potential. system of thepresent invention is equally well adapted for providing a digitalVmanifestation of a physical displacement. Arrangements foraccomplishing this are shown `in Fig. of the drawings, it being assumedthat switch 235 is now in its left-hand position and 'thatpswitch 237 isin its right-hand or open position.

There is provided a cathode-ray tube 300 having a fluorescent screen301, horizontal deflecting plates 302, vertical detlecting -plates 303,and an electron gun 3434. Associated with cathode-ray tube 300 is asuitable power supply 305, together with .conventional beam-.centeringmeans 306 and `3137, respectively associated with horizontalvfdeliecting plates 382y and vertical deecting plates 303. ,Disposed onthe axis of cathode-ray tube ,300 is a lens system 308, and a photocell309 having .an anode 316 connected to power supply 305 -and -a `cathode311 connected through a potentiometer 312 to ground. L/lovable arm 313of potentiometer 312 is connected through switch 235 (when in itsleft-hand position) to junction 236. Horizontal deecting plates 302 arecoupled by.

means of a capacitor 314 and switch '235 to translator output terminal21.19. Disposed between fluorescent screen 301 of cathode-ray tube '300and llens system-308 is a mask 315 which is arranged in any desiredmanner for linear lor rotational vertical movement in accordance The'with the physical displacement to lhe :measured and indi# cated. Oneedge 316 of mask 315 is so shaped as to'prof:

proportional relationship betweenthese 'two physical dimensions, vbut itwill be understood that any other con- `figuration of edge 316 may beemployed if desired.

In operation, let it trst be assumed that vcounter unit 13 (Fig. 3) isset at 0000 and mask 315 is at its initial position corresponding tozero physical displacement ,of the-unknown to be measured. Under thiscondition, `the trace of the electron beam on iluorescent screen 301 ofcathode-ray tube 300 is so disposed 'with respect to vmask 315 that animage of it just clears edge 316 of mask 315 and is projected bymeans'of lens system 308 on photocell' 369. This causes photocell 309 tobe highly .conductive, producing a positive potential across.potentiometer 312, a desired portion of this Ypotential being appliedthrough movable arm 313 and switch 235 to control electrode 248 ofgaseous discharge device 246, thereby causing this device to tire.Device 246 is promptly extinguished in the manner previously described.

Now let is be assumedthat mask 315 has moved downward by an amountcorresponding with the physical displacement .to b e measured. Mask 315now interrupts the projection of the trace image on photocell 309,causing the latter device to become non-conductive, so that there is noappreciable potential `drop across potentiometer 312. At the same time,counter unit 13 lhas begun to operate, causing an increasing potentialat translator output terminal 216. This potential is applied tohorizontal deflecting plates 302, ,causing a deilection of theelectronheam in'a direction toward edge 316 of mask 315. When thepotential at'termiual `210 reaches a suiciently high value, the electronbeam is dellected enough so that the image of its trace can pass edge316 of mask 315 and be projected by lens system 30S on photocell 309.This causes the latter device to become highly conductive, so that ahigh positive potential is developed across potentiometer 312 andapplied to control electrode J248 of gaseous discharge device 346, thuscausing it to iire and closingy gate 11 `in the manner previouslydescribed.

It will be apparent that the value now standing Vin counter unit 13 is afunction of the displacement of mask 315 and hence equal to or bearingadesired relationship to the ,physical displacement to lbe measured. Theremainder of the operating cycle for permitting manifestation of thecounter value ,and resetting ofthe counter in preparation for the `nextIoperating cycle is accomplished in vthe manner previously described inconnection with the lmeasurement of an electrical potential.

While therehave been ,shown and described-and pointed out thefundamental novel features of the Yinvention as applied toa preferredembodiment, fit will be 4understood that various omissions andsubstitutions and Acllanges in the form and details of the deviceillustrated and in itsk operation may be .made .by those skilled in .theart, withoutdeparting from the spirit ofthe invention. lIt is .theintention, therefore, to be limited only asl indicated l.by the scope ofthe following claims.

What is claimedis:

l. Apparatus for suppressing zresponses due Ato spurious relativelyshort-.period input `iluctuatious without aPPref' ciable elfect upon theresponse due to relatively 4longperiod input fluctuations, comprising:ftirst `and second input terminals; an `electron discharge ,deviceoperating as a cathode follower `and -having ,a cathode, a .controlelectrode and an anode; a frst impedance element connected between said7irst input ,terminal ,and said vcontrol .electrode; second and third:impedance .elements .connected ein series between said 'rst .and secondinput .termina1s,;said second impedance element :being 'capacitivelyreactive; .a connection between said .cathode .and the junction ofisaid13 second and third impedance elements, said third impedance elementserving as the sole load impedance of said device; and means formaintaining said anode at a fixed positive potential relative to saidsecond input terminal.

2. Apparatus for suppressing responses due to spurious relativelyshort-period input fluctuations without appreciable effect upon theresponse due to relatively longperiod input uctuations, comprising:first and second input terminals; an electron discharge device operatingas a cathode follower and having a cathode, a control electrode and ananode; a first impedance element lconnected between said rst inputterminal and said control electrode, the time constant due to said rstimpedance element and the input capacitance of said electron dischargedevice being of the order of the period of said short-periodfluctuations and small compared with the period of said long-periodfluctuations; second and third impedance elements connected in seriesbetween said rst and second input terminals; a connection between saidcathode and the junction of said second and third impedance elements,said third impedance element serving as the sole load impedance of saiddevice; and means for maintaining said anode at a fixed positivepotential relative to said second input terminal.

3. Apparatus for suppressing responses due to spurious relativelyshort-period input fluctuations without appreciable effect upon theresponse due to relatively longperiod input fluctuations, comprising:first and second input terminals; an electron discharge device operatingas a cathode follower and having a cathode, a control electrode and ananode; a first resistance element connected between said rst inputterminal and said control electrode, the time constant due to said firstresistance element and the input capacitance of said electron dischargedevice being of the order of the period of said short-periodiiuctuations and small compared with the period of said long-periodfluctuations; a capacitance element and a second resistance elementconnected in series between said flrst and second input terminals; aconnection between said cath-ode and the junction of said capacitanceand second resistance elements, said second resistance element servingas the sole load impedance of said device; and means for maintainingsaid anode at a fixed positive potential relative to said second inputterminal.

4. Apparatus for suppressing responses due to spurious relativelyshort-period input uctuations without appreciable effect upon theresponse due to relatively longperiod input fluctuations, comprising:first and second input terminals; an electron discharge device operatingas a cathode follower and having a cathode, a control electrode and ananode; a first impedance element comprising a resistance elementconnected between said first input terminal and said control electrode;second and third impedance elements connected in series between saidfirst and second input terminals, said second irnpedance elementcomprising a capacitively reactive element and said third impedanceelement comprising a resistance element; a connection between saidcathode and the junction of said second and third impedance elements,said third impedance element serving as the sole load impedance of saiddevice; and means for maintaining said anode at a xed positive potentialrelative to said second input terminal.

5. Apparatus for suppressing responses due to spurious relativelyshort-period input uctuations without appreciable effect upon theresponse due to relatively longperiod input fluctuations, comprising:rst and second input terminals; an electron discharge device operatingas a cathode follower and having a cathode, a control electrode and ananode; a first impedance element connected between said first inputterminal and said control elec` trode; second and third impedanceelements connected iu series between said rst and second input terminalssaid second element being capacitively reactive and, said thirdimpedance element comprising a resistance element shunted by acapacitance element; a connection between said cathode and the junctionof said second and third impedance elements, said third impedanceelement serving as the sole load impedance of said device; and means formaintaining said anode at a xed positive potential relative to saidsecond input terminal.

References Cited in the le of this patent UNITED STATES PATENTS2,406,790 Beatty et al. Sept. 3, 1946 2,422,205 Meacham June 17, 19472,591,247 Farnsworth Apr. 1, 1952

